This view of the twilight sky and Martian horizon taken by NASA's Curiosity Mars rover includes Earth as the brightest point of light in the night sky. Earth is a little left of center in the image, and our moon is just below Earth.

This frame from an animation from NASA's Mars rover Curiosity shows the rover drilling into rock target 'Cumberland.' The drilling was performed during the 279th Martian day, or sol, of the Curiosity's work on Mars (May 19, 2013).

This image from the Mars Hand Lens Imager on NASA's Mars rover Curiosity shows the patch of rock cleaned by the first use of the rover's Dust Removal Tool (DRT). The tool is a motorized, wire-bristle brush on the turret at the end of the rover's arm.

The two bodies in this portion of an evening-sky view by NASA's Mars rover Curiosity are Earth and Earth's moon. The rover's Mast Camera (Mastcam) imaged them in the twilight sky of Curiosity's 529th Martian day, or sol (Jan. 31, 2014).

Two instruments at the end of the robotic arm on NASA's Mars rover Curiosity will use calibration targets attached to a shoulder joint of the arm. The penny is a size reference giving the public a familiar object for perceiving size on Mars easily.

Two spacecraft engineers stand with three generations of Mars rovers developed at NASA's JPL, Pasadena, Ca. Front and center is a flight spare of Sojourner, left is a working sibling to Spirit and Opportunity, right is test rover Curiosity.

Two spacecraft engineers stand with three generations of Mars rovers developed at NASA's JPL, Pasadena, Ca. Front and center is a flight spare of Sojourner, left is a working sibling to Spirit and Opportunity, right is test rover Curiosity.

This grouping of two test rovers and a flight spare provides a graphic comparison of three generations of Mars rovers developed at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The setting is JPL's Mars Yard testing area.

This grouping of two test rovers and a flight spare provides a graphic comparison of three generations of Mars rovers developed at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The setting is JPL's Mars Yard testing area.

About the size of a small SUV, NASA's Curiosity rover is well equipped for a tour of Gale Crater on Mars. This impressive rover has six-wheel drive and the ability to turn in place a full 360 degrees, as well as the agility to climb steep hills.

NASA's Curiosity rover and its rocket-powered descent vehicle pose for a portrait at JPL's Spacecraft Assembly Facility prior to its launch on November 26, 2011 from the Space Launch Complex 41 on Cape Canaveral Air Force Station in Florida.

This set of views illustrates capabilities of the Mast Camera (MastCam) instrument on NASA's Mars Science Laboratory's Curiosity rover, using a scene on Earth as an example of what MastCam's two cameras can see from different distances.

This image illustrates the principals of a technique called 'laser-induced breakdown spectroscopy,' which the Chemistry and Camera (ChemCam) instrument onboard NASA's rover, Curiosity, will use on Mars.

This artist's impression Mars' Gale Crater depicts a cross section through the mountain in the middle of the crater, from a viewpoint looking toward the southeast. NASA's rover Curiosity will land in Gale Crater in August 2012.

Color coding in this image of Gale Crater on Mars represents differences in elevation. The vertical difference from a low point inside the landing ellipse for NASA's Mars Science Laboratory (yellow dot) to a high point on the mountain inside the crater.